Time-direction sensing circuit



Jan. 19, 1960 D. s. KUSHNER TIME-DIRECTION sENsING CIRCUIT 'Filed Maron so, 1955 2 Sheets-Sheet l Jan.19,196o n.8. KUSHNER l 2,922,107

I TIME-DIRECTION SENSING CIRCUIT Filed March 30, 1955 2 Sheets-Sheet 2 INVENTOR 2,922,107 Patented Jari. 19, 1960 'UNIE-DIRECTION SENSING .CIRCUIT David S. Kushner, Brooklyn, N.Y., assignor, by mesne assignments, to the United States-'of America as represented by the Secretary of the Navy Application March 30, 1955, Serial No. 498,121

6 Claims. (Cl. 324-68) This invention relates to a time-direction sensing circuit and, 'more particularly, to a time-direction sensing circuit which senses the order in the time of occurrence of pulses from three separate. pulseinputs Vapplied thereto.

The time-direction sensing circuit described-.herein is particularlyv suitable for'incorporation ina radar system; rit employs a chain of accurate timing pulsesat -a xed frequencytoderive a chain of pulses at a submultiple frequency Vand of`selectively adjustable phase. yThe'ad justable phase pulses are used as range marker pulses to enable accurate determination of the rangeof a target presented on the yrange indicator of the radar system. However, this time-direction sensing circuit is'useful whenever successive adjustableposition pulses may be `caused to start at a zero-time periodic reference pulse and be moved out andfback along a chain of accurately-spaced timing :pulses at the discretion of the operator.

A counter, capable of both addition and subtraction,

@is usedytoreport the progress` of the variable -position npulse-addiugzevery time-a timing pulse is crossed `while `the variable rposition Apulse ismoving away from the v`reference ,pulse, .and `subtracting every time ka timing pulse is-crossed while the variable position pulseis movingstoward.theareference pulse. Thus, at any time, the

.counter .will .indicate thenumber of timing .pulses between the variable position pulse and the referencepulse.

.It. is,.therefore, an object of this invention Lto. provide ...atime-,directionsensing circuit which provides Yan outoput..sigllal-.only-.\vhen pulses `applied theretofrom a plu- `irality of inputs foccur in a certain-sequential order.

-It.-isa .further object ,ofV this .invention to provide a :time-'direction sensing circuit which produces a rst `outputrsignal-only when a plurality of .inputs applied @thereto occur..in a first certain order and which pror duces va second` output signal only when the pulsesfrom `the,pluralityeoiinputs occur` in a second certain order.

YIt .is-a still-further object `of this invention to provide a time-.directionsensing circuit which can distinguish be- .tween the .movement of a variable position pulse, relative to a reference pulse, away .from and toward the ref- .erence pulse.

A'furtherfobject is to provide a superior range measur- Sing circuitf for -an echo ranging system.

AOther objects and many of the attendant advantages of-thisinvention will -be readilyappreciated as the same ybecomesl better understood by reference to the following detailed description when considered in connection with 'the accompanying drawings wherein:

` Figliis allblock diagram of a circuit incorporating the ,principles of'this invention; and

Fig.`2 'is 'a graph illustrating the relative time of occurrence of pulses appearing at various points in the circuit ofiFig. `1.

` Referring now toFigs. l and'2, timing pulse generator "102`g`eneratesal`iirst chainof timing pulses, 2a in Fig. l2;-whi'ch occur at aexed high frequency, suchas 100,000

A`kilocycles. l v102 is 'a second chain of ltiming pulses, 2b 1n Flg. 2, which includes Ialternate positive and negative pulses.

Also generated by timing pulse generator The positive and negative 2b timing pulses respectively -occurlat'the same xedffrequency as the 2a timing pulses.

Each positive 2bltiming pulse is spaced in time relative to-thepreceding 2a timing pulse by a given amount and each negative 2b 'pulse is spaced in time relative to the preceding positive 2b timing pulse by the same given amount. `Both timing pulses 2a and-2b` are derived from ftheoscillationsof-a single precision oscillator incorporated in timing pulsegenerator 102.

Also incorporated in timing .pulse generator 102 are delaymeans for `delayingthe positive and negative 2b timing pulses.

VTiminglpulsesla are applied to divider 104 whichpro- 'duces as an output reference pulses, 2c in Fig. 2, occurring3at-'a.sub-multiple, such as .001, of the iixed frequency of'timing\pulses-2a, Each referencepulse 2c, however,

occurs intime coincidence with a timing pulse 2a. Ref- -erence fpulses 2c trigger the transmitter 105 of a radar system, and are also applied to variable delay 106 to provide .as an -output variable position pulses, 2d in f-Fig. 2. iEach-variable position pulse 2d `follows a reflerenceipulse 2c'-by a time interval which `may be Varied at Vwill -anywlierebetween zero and -a pulse repetition periodof reference' pulses 2c by means'included in variable jdelay i106. "Further, variable vdelay 106 includes means for widening the variable-position pulses 2d, the

`pulsefwi'dth ofrvariablegpositionpulses`2d being greater 'thanf-thezpulse-width of timing pulses 2a and 2b, but less thanthe-'time interval between the time of occurrence of Aatirningfpulse 52a-and the next 'following positive tim- `ing pulse 2b.

The ltiming IpulsesZa and variable position pulses 2d are applied as first and second inputs to coincidence detector` 108. Coincidence detector 108 provides an outputzpulse, 2e inFig. l2, in response lto coincidence in the time of occurrence of a timing pulse 2a and a variableposition pulse 2d. Output pulses 2e are employed inthe associated radar system as range markers, being vapplied to range indicator 107. Target echoes received `by radar receiver 109' are delivered to the range indicator Timing pulses 2b and variable position pulses 2d are applied as rst and second inputs to coincidence detector 110. Coincidence detector-110 provides an output pulse,

l2J zn Fig. 2, in response to coincidence in the time of :occurrence of la positive timing pulse 2b and a variable 'position pulse 2d. Coincidence detector 110 also pro- Yduces anegative output pulse in response to coincidence `in thel time of occurrence of a negative timing pulse 2b and a variable position pulse 2d. The'negative output pulse isinverted by inverter 112 to provide a positive pulse, 2g in Fig. 2.

Pulses 2e are applied from coincidence detector 108 to flip-Hop 114, flip-flop 116 and one-shot multivibrator pulse Widener 118. Plip-op 114 has 2 stable positions designated as gate l and gate 2, respectively. Flip-Hop 116 has 2 stable positions designate as gate 3 and-gate 4,

., respectively. A pulse 2e from coincidence detector 10S plied asaninput to gated amplifier 122 and pulse output A second output from flip-fiop 114 is applied to gated x amplifier 124 'and is effective in enabling gated amplifier 124 to conduct when flip-fiop 114 is in its gate 2 position. A second output from flip-flop 116 is applied to gated amplifier 126 and is effective in enabling gated amplifier 126 to conduct when flip-flop 116 is in its gate 4 position..

Pulse 2f from coincidence detector 110 is applied as an input to gated amplifier 126 and pulse 2g from inverter ",112 is applied as an input teV gated amplifier 124.

Flip-flop 128 has two stable positions designated 'as gate 5 and gate 6, respectively, and flip-flop 130 has2 stable positions designated as gate 7 and gate 8,V respectively. The output of lgated amplifier 124 is applied to fiip-flop 128 and is effective in switching flip-flop 128 from its gate 5 to its gate 6 position. The output of gated amplifier 126 is applied to flip-flop 130 and is effec- .Y

tive in switching flip-Hop 130 from its gate 7 to its gate 8 position.

The output from flip-flop 128 is applied to gated amplifiers 132 and 134 and is effective in enabling gated amplifiers 132 and 134 to conduct when flip-flop 128 is in its gate 6 position. The output of ip-op 130is applied to gated amplifiers 136 and 138 and is effective in enabling gated amplifiers 136 and 138 to conduct whe fiip-ffop 130 is in its gate 8 position.

by a 2g pulse, a 2f pulse, another 2e pulse, etc. An add signal is produced only in response to 2e pulse being follower by a 2f pulse, a 2g pulse and another 2e pulse, and a subtract signal is produced only in response to a 2e pulseY being followed by a 2g pulse, a 2f and another 2e pulse.

To illustrate the functions of the various fiip-ops and gated amplifiers in producing the add and subtract signals, a typical sequence of operation will now be discussed. Assume that variable position pulse 2dhas just coincided with a 2a timing pulse to produce a 2e pulse, Vand that this 2e pulse has been registered by electromechanical counter 140, which vhas been initially set to indicate zero when variable position pulse 2d coincides with reference pulse 2c, that is, when variable delay 106 provides a zero delay. Flip-Hop 114 will then be in its gate 1 position, fiip-op 116 will be in its gate 3 position, flip-hop 128 will be in its gate 5 position and flip-flop 130 will be in'its gate 7 position. Therefore'only gated amplifiers 120 and 122 are enabled While gated amplifiers 124, 126, 132, 134,

- 136 and 138 are disabled. Y

As an example consider the variable position pulse 2d is moved farther'out relative to reference pulse 2c, up to the next following negative 2b timing pulse, then reversed and moved in towards reference pulse- 2c. Then following the original 2e pulse there will occur a 2f pulse, a 2g pulse, a 2f pulse, a 2e pulse, a 2g pulse, a 2f pulse, a 2e Pulse 2f from coincidence detector 110 is applied as j an input to gated amplifier 132 and pulse 2g from inverter 112 is appliedas an input to gated amplifier 138. The output of one-shot multivibrator pulse Widener 118, which has pulse 2e from coincidence detector 108 applied thereto, is applied as an input to gated ampliers 134 and 136.

The output of lgated amplier 132 is applied to ip-op 128 and is effective in switching flip-flop 128 from its gate 6 to its gate 5 position. The output of gated amplifier 138 is applied to fiip-flop 130 and is effective in switching fiip-flop 130 from its gate 8 position to its gate 7 position.

The output of gated amplifier 134 is applied tothe add actuating means of electromechanical counter 140 and the output of gated amplifier136 is applied to the subtract actuating means'of electromechanical counter 140. In addition, the add signal output of gated amplifier 134 is differentiated and applied to flip-flop 128, where the trailing edge thereof is effective in switching flip-flop 128 from its gate 6 to its gate 5 position. Similarly, the subtract signal output of gated amplifier 136 is differentiated and applied to flip-Hop 138, where the trailing edge thereof is effective in switching fiip-op 130 from its gate 8 to its gate 7 position.

The operation of the circuit shown in Fig. 1 will now be considered.

Since the range marker is a 2e pulse, obtained at the output of coincidence detector 108, the range marker will only be produced when the time of occurrence of a variable position 2d pulse coincides with the time of occurrence of a 2a timing pulse. To increase the range represented by the range marker, variable delay 106 is adjusted to move variable position pulse 2d further away from reference pulse 2c, so as to provide coincidence of variable position pulse 2d with a later occurring 2a timing pulse. As will be seen from the relative time of occurrences of timing pulses 2a and 2b shown in Fig. 2, a first 2e pulse will be followed in sequential order Vby a 2f pulse, a 2g pulse, another 2e pulse, etc. when variable position pulse 2d is moved farther away from reference pulse 2c. However, if variable delay 106 is adjusted to move variable position pulse 2d closer to reference pulse 2c, a first I2e pulse will be, followed in sequential order pulse, etc. y 3Qy `Aamplifier 122, thereby switching fiip-fiop 114'from its l gate 1 to its gate 2 position. This causes gated amplifier Since only gated amplifiers '120 and 122 are enabled, the 2f pulse which is first toappear is passed by gated 120 to be'disabled and gated amplifier 124 to be enabled.

The 2g pulse which appears next is therefore passed only by gated amplifier V124, thereby switching nip-Hop -128 from its gate 5 to its gate 6 position. enables gated amplifiers 132 and '134 'Y vShould a 2e pulse next appear it would lpass through gated amplifier 134 afterhaving been widened by oneshot multivibrator pulse Widener 118v and an add signal would be applied to the add actuating means ofelectromechanical counter 140.` One shot multivibrator pulse Widener 118 is employed to ensure that theaddjSgnal vhas enough energy to operate the add actuating means of the'electromechanical counter 140.

However, since the direction of the movable pulse is now'reversed, a 2f pulse, rather than a 2e pulse, next appears.

This 2f pulse passes through gated lamplifier 122,.but has no effect thereon, since flip-op 114 is already switched to its gate 2 position.V Also, this 2f pulse passes through gated amplifier 132 where it is effective in switching fiip-flop 128 back from its gate 6 to its gate 5 position, thereby disabling gated amplifiersv 132 and 134.

Next to appear is a 2e pulse which occurs at the same time relative to reference pulse 2c as the original 2e pulse.

' This 2e pulse is not counted by electromechanical counter 140, since gated amplifier 134 is now disabled. Howy ever, it is effective in switching fiip-flop 114 back from its gate 2 to its gate' 1 position.

Conditions now are exactly thev same as at'the start of operations, i.e. flip-flop 114 is in its gate k1 position, iiipiiop 116 is in its gate 3 position, flip-flop 128 is in its gate 5 positionfiipop 130 is in its gate 7 position, gated amplifiers 120 and 122 are enabled and gated amplifiers 12,4, 126, 132, 134,136 and 1387aredisab1ed.

As variable position pulse 2d continues to move toward reference pulse 2c, a 2g pulse is the next toY appear. This 2g pulse passes through gated amplifier 120 and switches flip-flop 116 from its gate3 to its gate 4'position, thus f enabling gated amplifier 126 and disabling gated amplifier 122. The 2f pulse which next occurs passes through gated amplifier 126 and switches ip-ffop 130 from its gate 7 Yto its gate 8 position.I This enables gated amplifiers 136 and 138. A.2 epulse, which is next to'appear, is applied te nip-flop 116 wherein switches :nip-nep `1116 backfire@ its gate 4 position to its gate 3 position. Also 2 pulse is'applied to still enabled gated amplifier 5136 through one shot multivibrator -pulse Widener 118 't 'provide a subtract signal which is applied t the subtract actuating means of electromechanical counter 140. The trailing edge of the subtract signal is differentiated Vand applied to iiip-fiop 130 to switch it back from its vgate 8 to its gate 7 position. The entire circuit is now again in the same condition as before the start of the operation.

Obviously many modifications and variations of the present invention are possible'in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

` I claim:

l. In combination, a source 'of pulses producing first, second and third separate pulse outputs, and time-direction sensing means coupled to said source and responsive to said first, second and third pulse outputs for producing a first signal only in response to the occurrence of a first pulse output being followed directly in sequential order by the occurrence of a second pulse output, a third pulse output and another first pulse output, said time-direction sensing means producing a second signal only in response to the occurrence of a first pulse output being followed in sequential order by the occurrence of a third pulse output, a second pulse output and another first pulse output, said time-direction sensing means comprises four ipflop circuits each having first and second stable positions and eight gated amplifiers, means for applying said second pulse output as an input to a first, second and third of said amplifiers, means for applying said third pulse output as an input to a fourth, fifth, and sixth of said amplifiers, means coupling a first of said fiip-fiop circuits to said first and second amplifiers for enabling said first amplifier to conduct only when said first fiip-iiop circuit is in its first position and enabling said second amplifier to conduct only when said first flip-flop circuit is in its second position, means coupling a second of said flip-flop circuits to vsaid fourth and fifth amplifiers for enabling said fourth amplifier to conduct only when said second hip-flop circuit is in its first position and enabling said fifth amplifier to conduct only when said second fiip-flop circuit is in its second position, means for applying the output of said first amplifier as an input to said second Hip-flop circuit to fiip said second flip-flop circuit from its first position to its second position, means for applying the output of said fourth amplifier as an input to said first flip-flop circuit to ip said first fiip-fiop circuit from its first position to its second position, means for applying said first pulse output to said first and second flip-flop circuits to iiop said first and second flip-flop circuits from their second position to their first position, means for applying said first pulse output as an input to the seventh and eighth of said amplifiers, means coupling a third of said flip-flop circuits to said third and seventh amplifiers to enable said third and seventh amplifiers to conduct only when said third nip-flop circuit is in its second position, means coupling the fourth of said fiip-fiop circuits to said sixth and eighth amplifiers to enable said siXth and eighth amplifiers to conduct only when said fourth flip-flop circuit is in its second position, means for applying the output of said fifth amplifier to said third fiip-fiop circuit to iiip said third flip-flop circuit from its first position to its second position, means for applying the output of said second amplifier to said fourth flip-hop circuit to iiip said fourth flip-flop circuit from its first position to its second position, means for applying respectively the output of said third amplifier and the trailing edge of the output of said seventh amplifier to said third flip-flop circuit to flop said third fiip-op circuit from its second position to its first position, and means for applying respectively, the output of said sixth amplifier and the trailing edge of the 6 'output of said eighth amplifier lto s'aidfurth flip-fibp Acir- `cuit to' 'op said' 'fourth -iip-p 'circuit fromy its second position to its first-position, the voutput of said seventh 'amplifier being' said first -`sig`nal and the output of said 'eighth amplifier being fsaid second signal.

2. The combinati' nfn aiccidane with claim l, wherein saidmeans for appl-yingsaid first pulse output as an input to" the `seventh and eighth oyf's'id amplifiers includes means for increasing Ythe 'width of each pulse of said first pulse output applied to said seventh and eighth amplifiers.

3. The combination in accordance with claim 2, furfther including an electior'ichanlcal dunter having add actuating means 'and subtrat actuating means, means applying said first signal to said 'counte'r for operating said add actuating meansy and rireans applying said second signal to said counter forope'rat'ing saidsubtract actuating means.

4. The combination in accordance with claim 3, wherein said source of pulses comprises pulse generating means for generating first, second and third chains of timing pulses at a given fixed frequency and a fourth chain of pulses at a repetition rate equal to a given sub-multiple of said given fixed frequency, each pulse of said second chain of pulses occurring between successive pulses of said first chain and each pulse of said third chain occurring between a pulse of said second chain and the next following pulse of said first chain, said pulse generating means including adjusting means for variably positioning the time of occurrence of pulses of said fourth chain relative to the time of occurrence of pulses of said first, second and third chains, and coincidence means coupled to said pulse generating means and responsive to said first, second, third and fourth chains of pulses for producing respectively said first, second and third pulse outputs in response to coincidence in the time of occurrence of a pulse from said fourth chain with a pulse from said first, second and third chains respectively.

5. Apparatus for use in an echo ranging equip-ment having a transmitter, a receiver, and a range indicator for indicating target echoes received by said receiver for enabling accurate determination of the range of a target from which echoes are returned, comprising: a timing pulse generator continuously providing timing pulses with a constant period and of pulse width that is small compared to pulse period; a divider coupled to said timing pulse generator and receiving timing pulse energy therefrom and in turn providing pulses that are of substantially the same width as the timing pulses Iand that are locked relative to the timing pulses and whose period is a constant and large multiple of the timing pulse period, for use in triggering said transmitter; selectively adjustable pulse delay means coupled to said divider and receiving some of the trigger pulse energy provided thereby and in turn providing corresponding pulses of pulse width that is on the order of the timing pulse width and that are delayed relative to the corresponding pulses from said divider for a time interval anywhere between zero and the period of one pulse from said divider according to the selected adjustment of said divider, means for delivering pulse energy to said range indicator in time coincidence with pulse energy from said adju-stable pulse delay means, whereby when said adjustable pulse delay means is adjusted so that the range indicator indicates that pulses from said pulse delay means coincide with pulse echoes from a target, the range of the target is directly proportional to the time displacement between the pulses from said divider and the corresponding pulses from said adjust-able pulse delay means; and counting and indicating means coupled to said timing pulse generator, to said adjustable pulse delay means and to said means for delivering pulse energy to said range indicator for providing a count of the number of timing pulse periods between the pulses from said divider and the corresponding pulses from said adjustable delay means,

erator, one ofw whichgdevicesA is ,said meanssfor delivering pulse energy to rsaidrange indicator, which'devices are each pulsed once in la predetermined spacedsequence during each pulse period of said timing pulse ygenerator, the spacings in the pulsing sequences being greater than the width of pulses from said adjustable delay means, each of said devices producing an output coincident with the aforementioned pulsing thereof only when a pulse from said adjustable delay `means arrives thereat at the same instant, wherebyl as Y said adjustable pulse delay means is adjusted the pulses therefrom cause said three devices to produce outputs in a sequence that either is the same or the reverse of the sequence in which said devices 8 are pulsed, the sequence of the outputs from said three devices depending upon whether the time displacement betweencorresponding pulses of said divider and adjustable pulsesdelay means is increasedor decreased by said adjustable pulseI delay means, said counting and indiat- Y ing means further including means coupled to said three devices and responsive to outputs therefrom to` increase or` decrease vthe count of timing pulse periods in accordance with the number of and the order of pulse sequences from said three devices.

References Cited in the file of this patent i UNITED STATES PATENTS 

